A YouTube user going by the name of Borman18 has leaked a pre-alpha gameplay video for Star Wars Battlefront III, which was cancelled causing the closure of its developers Free Radical.
The leaked footage shows a build from 2008 that was taken from the Xbox 360 version, although it appears unstable and very much incomplete. In the video you can see how easy it would have been to switch between land and space battles, and there's several clips of gameplay with the player controlling A-wings, the Millenium Falcon, Luke Skywalker, etc...
The latest rumourthat Spark Unlimited are working on Star Wars Battlefront 3, but we'll have to wait and see to know for sure. It could be that something will be revealed at E3 2012.